Field of the Invention
This invention relates to improvements in portable fire extinguishers. More particularly, the present invention relates to a fire extinguisher that uses a replaceable gas cartridge that provides a propellant to push fire extinguishing media outside of the fire extinguisher.
Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Most portable fire extinguishers are of a similar design where the fire extinguishing powder is contained in a continuously pressurized chamber. Fire extinguishers of this type require scheduled maintenance by trained and certified technicians with certification issued by the fire marshal for each state. This maintenance involves discharging, cleaning, and refilling the extinguisher. If not done periodically, the powder within the chamber becomes compacted and/or the pressure within the chamber may leak and be insufficient to propel the powder out of the dispensing nozzle. If maintenance is not done correctly, moisture absorption by the extinguishing powder will cause caking and block the dispensing nozzle. The aforementioned conditions would prevent the proper dispensing of extinguishing powder when needed.
Current extinguishers are open to wear and tear because of the constant pressure and tear down process. When serviced they are discharged into a recycling chamber and all the parts must be disassembled and cleaned. All the pressure rings must be replaced and every part must then be re-assembled with new powder being placed within the chamber prior to pressurizing the chamber. The servicing of current fire extinguishers often creates more wear and tear on the fire extinguisher than when it is used to extinguish a fire.
U.S. Pat. No. 6,189,624 issued to James on Feb. 20, 2001 and Japan Patent Number JP 9,225,056 issued to Yamazaki Tomoki on Sep. 2, 1997 discloses fire extinguishing mechanisms where the chamber is not continuously pressurized, and the pressurized cartridge is a separate entity integrated within the chamber. While these patents disclose a separate pressurized cartridge, the cartridge is not located in a position that is easy to service, replace, or inspect. This minimizes the ability determine the charge level of the pressurized cartridge.
U.S. Pat. No. 2,541,554 (“U.S. '551”) issued to C H Smith on Feb. 13, 1951 and Russian Patent Number RU 2,209,101 (“RU '101”) issued to Glavatski G. D. Et Al. Nov. 2, 2002 discloses a fire extinguisher with an external CO2 gas cartridge. In the case of U.S. '554 the CO2 gas cartridge sits on top of the fire extinguisher chamber and is not integrated within the handle of the fire extinguisher. In the case of RU '101 the CO2 gas cartridge is external to the extinguisher and is connected to the extinguisher with a pipe or hose. While both of these patents disclose a CO2 cartridge that is external to the chamber, neither of them is placed in the handle to allow a configuration of the fire extinguisher that is simple to inspect and replace.
U.S. Pat. No. 7,128,163 issued on Nov. 21, 2006, U.S. Pat. No. 7,318,484 issued on Jan. 15, 2008 and U.S. Pat. No. 7,793,737 issued Sep. 14, 2010, all to Hector Rousseau disclose a fire extinguisher with a gas cartridge in the handle and a fluffing mechanism. While these patents have similar features, the gas cartridge is oriented to discharge vertically upwards. When gas is discharged from a cartridge containing compressed liquefied gas, such as CO2, evaporation must occur from the contained liquid in order to maintain thermodynamic equilibrium with the cartridge. Heat is required to drive the evaporation, and if the available heat from the surrounding cartridge environment is insufficient, the compressed liquefied gas temperature and pressure will drop. For CO2, if the pressure drops below 75 psig, liquid CO2 will solidify into dry ice. Since cartridge-style fire extinguishers are usually used immediately after puncturing the cartridge, any dry ice formed will not have time to absorb enough heat to phase change into gas and contribute to the effective discharge of the fire extinguisher. This effect is magnified at low environmental temperatures, where existing commercial cartridge-style fire extinguishers have been measured to waste 40% by mass of the CO2 charge when conditioned at −40° C. However, even though this gas is unused during typical discharge, the extinguisher must be structurally designed based on the full pressurizing gas load, leading to less than optimal designs. In addition, based on the unique properties of CO2, torturous paths between the fire extinguisher main chamber and the cartridge must be avoided to minimize the risk of blocking the flow path with dry ice or freezing valves due to resulting low temperatures from CO2 expansion.
Due to the pressurized condition that exists with pressurized fire extinguishers, the opening where powder is placed into the extinguisher is limited due to the structural requirement to maintain pressure within the chamber at all times. The proposed application eliminates this need by providing an external gas cartridge, thus allowing the chamber to exist in a normally un-pressurized condition. Because the chamber is not under pressure the top opening of the extinguisher can be enlarged to allow easier filling of the fire extinguisher with powder, or checking the amount and or condition of the powder within the chamber.
What is needed is a fire extinguisher with a replaceable gas cartridge where the gas cartridge is oriented to discharge only liquid propellant into the body of the extinguisher and the fire extinguisher further has a fluffer that is accessible from outside the chamber, and the chamber has an enlarged top opening for filling the extinguisher. The proposed fire extinguisher provides this solution by providing a fire extinguisher with an external gas cartridge oriented to discharge downward, external mechanism to actuate an internal fluffer, and a large opening. By discharging the compressed liquefied gas downward, liquid is discharged into the fire extinguisher, and as such, the cartridge does not need to absorb nearly as much heat to drive the necessary evaporation to maintain temperature and pressure within the cartridge above the triple point, and thus, solidification of the propellant is avoided. For compressed liquefied CO2, this concept has been experimentally demonstrated to discharge nearly 100% of the CO2 from the cartridge, even with the fire extinguisher preconditioned to −40° C.